Sample should be without replacement

[robbat2]

The definition of sample is that it should be WITHOUT replacement.
From the Rubydocs on Array#sample:
The elements are chosen by using random and unique indices into the array in order to ensure that an element doesn’t repeat itself unless the array already contained duplicate elements.

[jaysonvirissimo]

@robbat2 I just made an alternative to weighted_randomizer partly to correct this issue.